JP2916773B2 - One-component developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one-component developing apparatus for developing an electrostatic latent image using a one-component toner.

2. Description of the Related Art In electrophotography, cascade development, magnetic brush development, and liquid development are well known as methods for developing an electrostatic latent image.

On the other hand, other important developing methods include US Pat. No. 2,895,847.
There is a transfer development method using a toner carrying member called a donor disclosed in the specification. The transfer development method described in this patent specification includes the following two methods: (1) when the toner layer is not in contact with the photoconductor and the toner flies through this gap; and (2) when the toner layer is in rotational contact with the photoconductor. (3) This is a general term for the case where the toner layer comes into contact with the photoreceptor and the image area slides, and is well known as a touch-down development method.

As a one-component developing device of the touchdown developing method, a device using a magnetic toner and a device using a non-magnetic toner are known.

FIG. 14 is a schematic diagram of an example of a magnetic one-component device. In FIG. 14, reference numeral 1 denotes a photoconductive drum (electrostatic latent image carrier) capable of holding the electrostatic latent image 2, and the developing device is disposed close to a position facing the photoconductive drum 1. I have. The developing device has a hopper 3 for containing a magnetic one-component developer 4 and a magnet roll 5 in which a plurality of magnetic poles fixed so as not to rotate inside are alternately arranged. 5, a non-magnetic cylindrical developing sleeve 6 rotatably supported around the developing sleeve 5, and a toner amount regulating member disposed in pressure contact with the developing sleeve 6 to regulate the amount of magnetic toner adhering to the developing sleeve 6. The developing sleeve 6 and the toner amount regulating member 7 are disposed in the hopper 3, and the developing sleeve 6 is disposed near the photoconductive drum 1 in a developing area.

In such a developing device, the magnetic one-component developer 4 stored in the hopper 3 is held on the surface of the developing sleeve 6 by the magnetic force of the magnet roll 5, and adheres to the developing sleeve by the toner amount regulating member 7. After the toner amount is regulated to 1 mg / cm ² , the rotation of the developing sleeve 6 causes the photoconductive drum 1 and the developing sleeve 6 to be sent to a developing area where they face each other. A DC superimposed AC voltage is applied to the developing sleeve 6 from an AC high-voltage power supply 8 and a DC power supply 9, and a photoconductive drum 1 is formed in a developing area (an area where the photoconductive drum 1 and the developing sleeve 6 are opposed to each other). The upper electrostatic latent image 2 is developed with a magnetic one-component developer. (For example, JP-A-54-51848, JP-A-58-146249, U.S. Pat. Nos. 3,372,675 and 3,426,730) FIG. 15 shows an example of a one-component developing apparatus using a non-magnetic toner. (Japanese Patent Laid-Open No. 60-53975).

In this apparatus, a non-magnetic one-component developer 4 is accommodated in a hopper 3, and the one-component developer 4 is supplied by a supply roll 13 rotating in the direction of an arrow at the same peripheral speed as the developer carrier 14. It is supplied to the carrier.

On the developing sleeve 6 of the developer carrier 14, a soft elastic member of a toner amount regulating member 7 comprising a spring material 11 and a soft elastic member 12 is provided.
12 are provided so as to contact with a predetermined pressure. The one-component developer 4 supplied to the developer carrier 14 is transported to the position of the toner amount regulating member 7 by rotation of the developer carrier,
After being formed into a predetermined uniform thin layer and given a predetermined charge, it is sent to a position (developing area) facing the semiconductive drum 1. An alternating voltage is applied to the developer carrier, and the developer flies to the semiconductive drum 1 due to an alternating electric field generated in a gap between the semiconductive drum 1 and the developer carrier 14, and the electrostatic latent voltage is applied. Image development takes place.

Problems to be Solved by the Invention In such a one-component developing device, the life of the toner amount regulating member is determined by the thickness of the soft elastic member and the degree of friction. However, by merely increasing the thickness of the soft elastic member, the contact area with the developing sleeve increases with the friction of the soft elastic member, and the effective pressing force decreases. A stable toner layer cannot be obtained. Further, even if the contact width of the soft elastic member is limited so as not to increase the contact area, as the abrasion progresses, the pressure contact stress at the toner inflow portion increases, the toner cannot enter, and the There is a problem that unevenness occurs in the toner layer.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a one-component developing apparatus which eliminates the above-mentioned disadvantages of the prior art and can stably obtain a toner layer on a developing sleeve for a long time.

Means for Solving the Problems The present invention relates to a developer carrier facing an electrostatic latent image carrier, a unit for supplying a developer onto the developer carrier, and a toner for pressing the developer carrier. The toner amount regulating member to form a thin layer of the developer on the developer carrying member and impart an electric charge, and the developer formed in the thin layer is transferred to the electrostatic latent image holding member. In the one-component developing device that is attached to the electrostatic latent image for visualization, the toner amount regulating member includes a support made of a spring material having a tensile strength of 20 kgf / mm ² or more and a proof stress of 10 kgf / mm ² or more, and the support A soft elastic member provided at a contact portion of the body with the developer carrying member, and the soft elastic member is an end of the developer carrying member on a toner inflow side surface following a surface of pressing the developer carrying member. The developer carrier is supported by the above-described support so that an edge thereof contacts the developer carrier. The soft elastic member is pressed in the center direction, and the soft elastic member has a tangent line at the contact point between the edge of the side surface on the toner inflow side and the developer carrier, and the side surface of the soft elastic member on the toner inflow side. DOO toner inflow angle theta _s initial state formed by, characterized in that it is set to be a relationship that satisfies the following equation.

(Wherein, θ _s represents the toner inflow angle in the initial state formed between the side of the soft elastic member on the toner inflow side and the surface of the developer carrier, r represents the radius of the developer carrier, and t represents the thickness of the soft elastic member. Further, in the one-component developing apparatus of the present invention, the length LR of the soft elastic member in the direction perpendicular to the axial direction of the developer carrier is determined when the soft elastic member comes into contact with the developer carrier. When the length of the contact portion in the circumferential direction is 1N (hereinafter, these lengths may be referred to as “width”), it is preferable to satisfy at least the following expression.

1/2 lN ≦ LR ≦ 4 lN In a preferred embodiment of the one-component developing apparatus of the present invention, the soft elastic member has a surface energy of 30 dynes / c.
It is preferable to use a rubber agent having a hardness of 30 m or less and a hardness of 30 to 70 mm.

In the present invention, the toner inflow angle θ _{s in the} initial state formed by the side of the soft elastic member on the toner inflow side and the surface of the developer carrying member.
As shown in FIG. 3, the edge of the soft elastic member 12 in the initial state on the developer inflow side on the toner inflow side is
It means the angle between the tangent at the point of contact with the semiconductive sleeve 6a as the developer carrier and the side surface of the soft elastic member. Therefore, when the wear of the soft elastic member progresses, the toner inflow angle θT increases as the contact point between the side surface of the soft elastic member and the surface of the semiconductive sleeve shifts. The increase amount θA of the toner inflow angle can be obtained from the radius r of the semiconductive sleeve and the abrasion depth a of the soft elastic member (meaning the thickness of the soft elastic member lost by abrasion) according to the following equation. .

Therefore, the toner inflow angle θT when the wear of the soft elastic member progresses is θT = θS + θA.

By the way, as is clear from the test results in FIG. 9 described later, if the toner inflow angle θT is in the range of 25 ° ≦ θT ≦ 90 °, good results can be obtained. The maximum value θTmax is obtained when the thickness t of the soft elastic member and the wear depth a are equal, (Wherein, θ _s represents the toner inflow angle in the initial state formed between the side of the soft elastic member on the toner inflow side and the surface of the developer carrier, r represents the radius of the developer carrier, and t represents the thickness of the soft elastic member. Therefore, in order to achieve the intended purpose of the present invention until the soft elastic member is completely worn, the following equation is required. It is sufficient to set the theta _s to satisfy.

In the present invention, the support of the toner amount regulating member needs to have a tensile strength of 20 kgf / mm ² or more and a proof stress of 10 kgf / mm ² or more. Tensile strength is lower than 20 kgf / mm ^2, the strength is lower than 10 kgf / mm ^2, easy soft elastic member attached to the spring member is generated is parallel undulations in the axial direction of the sleeve, a uniform toner layer I can't get it.

Operation The operation of the present invention will be described in comparison with the related art. Fifth
FIGS. 5A and 5B are diagrams for explaining a state in which development is performed using a conventional soft elastic member having a limited contact width of the soft elastic member. FIG. 5A is a schematic cross-sectional view, and FIG. (C) shows the stress distribution when the soft elastic member is worn. As is apparent from this figure, the stress at the toner inflow end of the soft elastic member is low at the initial stage (FIG. 5 (b)).
The stress at the toner inflow end increases (FIG. 5 (c)). Therefore, the amount of toner adhered on the sleeve is reduced, causing a decrease in copy density.

On the other hand, in the present invention, since the soft elastic member has the above-described configuration, the above-described problem is solved. FIG. 4 illustrates this.
(A) is a schematic sectional view in the case of developing using the soft elastic member in the present invention, and (b) to (d) are diagrams for explaining a stress distribution state. In the present invention, as the soft elastic member wears, the stress distribution of the force PB received from the spring material 11 at the contact portion between the soft elastic member 12 and the semiconductive sleeve 6a becomes an averaged state (fourth embodiment). Figure (b). However, the toner inflow side surface of the soft elastic member has the toner inflow angle θ in the initial state.
_s is set and has a toner inflow angle θT, so that a static toner area is formed in a triangular area formed between the toner inflow side surface of the soft elastic member and the semiconductive sleeve 6a (fourth). (Parts shown by oblique lines in FIG. (A)). The stationary toner in the still toner area, for pressing the toner inflow side with a force FT when moved by rotation of the sleeve, the force F _s is generated to lift the soft elastic member by the action of the wedge (FIG. 4 (c) ). Therefore, in the present invention, the stress distribution in the soft elastic member is the sum of these two forces (FIG. 4 (d)), and the stress distribution at the toner inflow end is reduced, so that the toner easily enters. Therefore, even if the soft elastic member is worn, the amount of toner adhered to the developing sleeve does not decrease as in the related art.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of a magnetic one-component developing device of the present invention. In the figure, reference numeral 1 denotes a photoconductive drum (electrostatic latent image carrier) having a surface made of a positively charged inorganic photoreceptor, which is uniformly charged by a charging means (not shown) and then exposed. Is done. The surface potential at this time is, for example, 80
0 V and the potential of the background part is 120 V. Reference numeral 3 denotes a hopper for storing a magnetic one-component developer 4.
Consists of a magnetic toner containing 48% by weight of magnetic powder. Reference numeral 5 denotes a magnet roll having a magnetic pattern as indicated by N and S in the figure, and is fixed to a frame (not shown). 6a is a phenolic resin having a specific resistance of 4.2 × 10 ⁷ Ω · cm, formed into a cylindrical shape having a thickness of 1.0 mm, and the surface thereof is polished in the longitudinal direction so that RZ = 4.3 μm with 10-point average roughness of JIS. A semiconductive sleeve (developer carrier), which is rotatably supported around the magnet roll 5. 11 is 0.1m thick
This is a spring material using non-magnetic stainless steel SUS303 3 / 4H material with a tensile strength of 95 kgf / mm ² and a proof stress of 68 kgf / mm ² . A soft elastic member 12 made of silicone rubber having a rubber hardness of 50 ° is attached to the tip end of the spring material by vulcanization bonding to form a toner amount regulating member 7.

The shape of the soft elastic member 12 has a thickness of 3 m as shown in FIG.
It has a trapezoidal shape of m, a base of 5 mm, and a top of 2 mm. The bottom is a surface to be vulcanized and bonded to the spring material 11, and the top is in contact with the semiconductive sleeve 6a. The hypotenuse is directed in the toner inflow direction, and when the soft elastic member is pressed against the semiconductive sleeve, the angle θ _s formed between the hypotenuse and the tangent to the semiconductive sleeve.
Is set to 45 ° so that the angle θR between the hypotenuse and the base is 45 °.
Set to ゜. Also, the spring material 11 causes the soft elastic member 12 to face the semiconductive sleeve 6a with a force of 100 g / cm at a position 145 ° behind a reference line (0 °) connecting the developing position and the center of the magnet roll. Like the angle of deflection of the spring material
It is set at 80 ゜.

The toner adhesion amount regulated by the toner amount regulating member constituted by the spring material 11 and the soft elastic member 12 was 1.2 mg / cm ² per unit surface area of the semiconductive sleeve.

The one-component developing device having the above-described configuration is provided with a semiconductive sleeve.
When placed in the copying machine such that the gap width between 6a and the photoconductive drum 1 was 230 μm, the toner on the semiconductive sleeve did not come into contact with the photoconductive drum. Applying a DC superimposed AC voltage having a frequency of 2.4 KHz, a peak-to-peak voltage of 2400 V, and a DC component of -200 V to the semiconductive sleeve 6 a using the AC power supply 8 and the DC power supply 9 to perform development, a very clear image is obtained. Was done.

In addition, even if the copying operation is performed for a long time and the wear of the soft elastic member progresses, the toner layer on the semiconductive sleeve is not affected at all, and the semiconductive sleeve and the spring material come into direct contact. Until then, clear images were obtained.

Comparative Example FIGS. 6 and 7 illustrate the state of a soft elastic member in the prior art. FIG. 6 shows that the width LR of the soft elastic member 12 having a thickness of 3 mm attached to the spring material 11 is sufficiently larger than the width LN of the contact surface with the semiconductive sleeve as the developer carrier (LR = 30mm), the center part of which is in contact with the semiconductive sleeve 6a at a pressure of about 100g / cm, and after collecting about 90,000 copies, the toner amount regulating member and the semiconductive The state of the sleeve is shown. In this case, the width LN of the contact surface with the semiconductive sleeve
= 15 mm. In this case, when the soft elastic member wears, the width LN of the contact surface with the semiconductive sleeve increases, the effective pressing force decreases, and the toner adhesion amount on the semiconductive sleeve increases. Defects occurred in copy quality such as thickening of the image and background fog.

FIG. 7 shows that the width of the soft elastic member 12 attached to the spring material 11 is set to 5 m in order to limit the contact width with the semiconductive sleeve 6a.
Shows the case when m is set. With the wear of the soft elastic member, the stress distribution on the contact surface changes, and the stress on the toner inflow portion increases,
The toner cannot enter the contact portion between the soft elastic member and the sleeve. Therefore, in the case shown in FIG. 7, the amount of toner adhering to the sleeve was reduced, causing a decrease in copy density.

When a comparison was made between the one-component developing device of the above embodiment and the developing device of the comparative example, the results shown in FIG. 8 were obtained.

FIG. 8 is a graph showing the relationship between the number of copies and the toner adhesion amount. In the figure, ○ indicates the case using the one-component developing device of the embodiment of the present invention, △ indicates the case where the toner amount regulating member shown in FIG. 6 is used, and □ indicates the toner amount regulating member shown in FIG. Is shown. As is clear from this figure, in the embodiment of the present invention, a constant toner adhesion amount can always be obtained as compared with the prior art.

Next, the relationship between the toner inflow angle θT and the amount of toner attached to the worn soft elastic member corresponding to the case of copying 300,000 sheets was examined. When the test was conducted with the initial amount of toner attached being 1.2 mg / cm ² , the results shown in FIG. 9 were obtained.
In FIG. 9, the vertical axis indicates the amount of toner adhered during wear corresponding to 300,000 copies, the horizontal axis indicates the toner inflow angle θT, and A indicates an area where a clear copy can be obtained. From this result, the toner inflow angle θT is 25 ° ≦ θT ≦ 90
It was found that good results could be obtained if the value was within the range of ゜. This toner inflow angle theta _s eggplant initial state of the soft elastic member and the developer carrying member surface means that good results are obtained when having the following relationship.

Next, the rubber hardness of the soft elastic member was changed by setting the toner inflow angle θT to 90 °, and the relationship between the rubber hardness and the toner adhesion amount on the worn soft elastic member corresponding to 300,000 copies was examined. Was. Initial toner adhesion 1.2mg / cm ²
The results shown in FIG. 10 were obtained when the test was performed under the conditions described above. In FIG. 10, the vertical axis indicates the amount of toner adhered during abrasion corresponding to 300,000 copies, the horizontal axis indicates rubber hardness, and A indicates an area where a clear copy can be obtained. As is clear from FIG. 10, it was found that good results were obtained in the range of rubber hardness of 30 ° to 70 °.

Furthermore, the length of the soft elastic member in a direction perpendicular to the axial direction of the developer carrying member and the circumferential length of a contact portion when the soft elastic member contacts the developer carrying member in the initial state (hereinafter, referred to as “the soft elastic member”) The relationship between the contact width and the amount of toner adhered to the worn soft elastic member, which is equivalent to 300,000 copies, was investigated. The relationship shown in FIG. 11 was found. In FIG. 11, the vertical axis is 300,000
Indicates the amount of toner attached at the time of final wear corresponding to one sheet copy,
The horizontal axis indicates the final contact width LN with the rubber semiconductive sleeve, and A indicates the area where a clear copy can be obtained. From this result, it has been found that when the bottom width of the soft elastic member is set in the range of the following expression, a stable toner adhesion amount can be obtained.

1 / 2LN ≦ LR ≦ 4LN (where LR is the length of the soft elastic member in a direction perpendicular to the axial direction of the developer holding member, and 1N is the length of the soft elastic member when the soft elastic member contacts the developer holding member. FIG. 12 is a schematic view showing another example of the one-component developing apparatus using a non-magnetic toner according to another embodiment of the present invention.

In this apparatus, a non-magnetic one-component developer 4 is accommodated in a hopper 3, and the developer 4 is supplied by a supply roll 13 rotating in the direction of an arrow at the same peripheral speed as the developer carrier 14. Supplied to.

On the surface of the developer carrying member 14, a toner amount regulating member composed of the spring material 11 and the soft elastic member 12 having the shape described in the above embodiment is provided so as to come into contact with a predetermined pressure. The one-component developer 4 supplied to the developer carrier 14 is transported to the position of the toner amount regulating member by the rotation of the developer carrier, and is formed into a predetermined uniform thin layer and a predetermined charge. Thereafter, the sheet is sent to a position (developing area) facing the semiconductive drum 1. An alternating voltage is applied to the developer carrier by a DC power supply 9 and an AC high-voltage power supply 8. The alternating electric field generated in the gap between the semiconductive drum 1 and the developer carrier 14 causes the developer to be semiconductive. It flies to the drum 1 and develops the electrostatic latent image 2. Incidentally, reference numeral 15 denotes a seal member.

FIG. 13 shows another embodiment of the soft elastic member. In this example, the toner inflow side surface of the soft elastic member 12 has a shape inclined in an arc shape.

Effect of the Invention Since the one-component developing device of the present invention includes the soft elastic member having a predetermined shape and the toner amount regulating member made of a spring material as described above, the wear of the soft elastic member progresses. However, the developer can always be stably adhered to the semiconductive sleeve, and the copying operation can be performed over a long period of time with a constant amount of adhered toner. Therefore, a copy image of good image quality can be obtained over a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of one embodiment of the present invention, and FIG.
FIG. 3 is an explanatory view illustrating the shape of the soft elastic member used in the embodiment of the present invention, FIG. 3 is an explanatory view illustrating the toner inflow angle in an initial state, and FIG. 4 is a stress distribution state illustrating the operation of the present invention. FIG. 5 is an explanatory view showing the state of stress distribution in the prior art for explaining the operation of the present invention, and FIG.
FIGS. 7 and 8 are explanatory views illustrating the shape of the soft elastic member in the comparative example, FIG. 8 is a graph illustrating the effect of the embodiment of the present invention, and FIG. 9 is a relation between the toner inflow angle and the toner adhesion amount. FIG. 10 is a graph showing the relationship between the rubber hardness and the amount of toner adhesion, FIG. 11 is a graph showing the relationship between the contact width of the soft elastic member and the amount of toner adhesion, and FIG. 12 is another embodiment of the present invention. FIG. 13 is an explanatory view for explaining the shape of another example of the soft elastic member used in the present invention, and FIGS. 14 and 15 are schematic structural views of a conventional one-component developing device. DESCRIPTION OF SYMBOLS 1 ... Semiconductive drum, 2 ... Electrostatic latent image, 3 ... Hopper, 4 ... One-component developer, 5 ... Magnet roll, 6
Developing sleeve 6a Semi-conductive sleeve 7 Toner amount regulating member 8 AC high voltage power supply 9 DC power supply 11 Spring material 12 Soft elastic member 13 Supply roll, 14: developer carrier, 15: seal member.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Suwabe 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. Ebina Office (56) References JP-A-62-242975 (JP, A) JP-A-62- 96981 (JP, A) Actually open 621-242064 (JP, U)

Claims (2)

(57) [Claims] An image forming apparatus includes: a developer carrier facing an electrostatic latent image carrier; a unit for supplying a developer onto the developer carrier; and a toner amount regulating member for pressing the developer carrier. ,
The toner amount regulating member forms a thin layer of the developer on the developer carrying member and gives an electric charge, and the developer formed in the thin layer adheres to the electrostatic latent image on the electrostatic latent image holding member. In the one-component developing device, the toner amount regulating member is made of a spring material having a tensile strength of 20 kgf / mm ² or more and a proof stress of 10 kgf / mm ² or more, and the developer carrier of the support. And a soft elastic member provided at a contact portion with the developer carrier. The soft elastic member has an edge on the developer carrier side at a side of the toner inflow side following the surface of pressing the developer carrier, and is connected to the developer carrier. The support is pressed against the center of the developer carrier by the support, and the soft elastic member is provided at a contact point between the edge of the side surface on the toner inflow side and the developer carrier. And the side surface of the soft elastic member on the toner inflow side is Toner inflow angle of to the initial state θ
A one-component developing apparatus, wherein _s is set so as to satisfy the following expression. (Wherein, θ _s represents the toner inflow angle in the initial state formed between the side of the soft elastic member on the toner inflow side and the surface of the developer carrier, r represents the radius of the developer carrier, and t represents the thickness of the soft elastic member. ) 2. The one-component developing device according to claim 1, wherein the length of the soft elastic member in a direction perpendicular to the axial direction of the developer carrier is in a range satisfying at least the following expression. apparatus. 1 / 2LN≤LR≤4LN (where LR is the length of the soft elastic member in a direction perpendicular to the axial direction of the developer carrying member, and 1N is the length of the soft elastic member when it contacts the developer carrying member. (Indicates the circumferential length of the initial contact part)